Currently, the most commonly used electrical energy production technologies still make massive use of fossil fuels, which are used for generating steam. The generated steam imparts rotation of movement to a turbine, the shaft of which is mechanically coupled to a rotor of an electrical generator. Upon rotation of the rotor, electrical energy is produced, the magnitude of which is a function, among other things, of the rotation of speed of the rotor and the size of the generator. Using coal, petroleum or gas for producing electricity has several drawbacks. For example, transportation of coal and fuel is expensive and raises the final cost of the electrical energy that is produced using them. In addition, using coal and fossil fuel greatly pollutes the environment. These, and other, drawbacks encourage the development and use of other alternative technologies, and in particular technologies that are based on the exploitation of energy of wind, sea waves and solar energy.
Currently, there are technologies that exploit solar energy in two ways. The first way involves exploiting solar energy to directly heat a liquid, usually water, for, e.g., heating the interior of an apartment. According to this method, a conduit, through which the liquid (normally water) passes, is laid in a ‘heat absorbing environment’ where it is exposed to the solar energy. The ‘heat absorbing environment’ is normally a flat black metal platform, on which the conduit is coiled to absorb as much of the solar energy as possible. Since solar systems of this kind are in broad use, no further description of will be given herein with respect to their functioning and structure. The conversion efficiency of this technology is known to be very low (usually not more than 10%).
The second way to exploit solar energy is to convert it into electricity. Direct Thermal to Electric Conversion (DTEC) technologies are known. Recent advances in thermal-to-electric conversion technologies such as thermoelectrics and thermophotovoltaics have demonstrated the potential for achieving high-efficiency, solid-state electric generators that could convert thermal energy into electricity. However, these technologies are very expensive, and they produce direct current, which is problematic because many electricity appliances use alternating current.
The efficiency, by which heat can be converted into electricity, is limited by the theoretical maximum efficiency of the Carnot cycle, which is known to be a cycle (of expansion and compression) of an idealized reversible heat engine that does work without loss of heat. Although the Carnot efficiencies drop as the temperature differences between hot and cold side decreases, the theoretical maximum conversion efficiencies can range from a low of about 40% to a high of about 77%, depending on the used thermal sources. However, current Direct Thermal to Electric Conversion (DTEC) technologies fall far short of Carnot conversion efficiencies and, in many cases, fail to exhibit sufficient power densities to meet requirements for many commercial applications.
It is a known phenomenon that a movement of an electrically conducting wire across a magnetic field induces an electric current in the wire, which depends, among other things, on the flux of the magnetic field and on the velocity of the wire. Likewise, a flow of a ‘liquified’ magnet inside a conduit, around which a conducting wire is coiled, can induce electric current in the wire.
In recent years, researchers have prepared ferrofluids, which have the fluid properties of a liquid and the magnetic properties of a solid. The ferrofluids contain tiny particles of a magnetic solid suspended in a liquid medium. A ferrofluid is a stable colloidal suspension of sub-domain magnetic particles in a liquid carrier. The particles, which have an average size of about 100 Å (10 nm), are coated with a stabilizing dispersing agent (surfactant) which prevents particle agglomeration even when a strong magnetic field gradient is applied to the ferrofluid. A typical ferrofluid may contain (by volume) 5% magnetic solid, 10% surfactant and 85% carrier (liquid). Ferrofluids are commercially available.
A notion, as to the properties and actual and possible uses of ferrofluids may be found in the following websites:    http://mrsec.wisc.edu/edetc/ferrofluid;    http://www.physicscentral.com/action/action-03-07-print.html;    http://www.ferrotec.com/usa/ferrofluid_technology_overview.htm;    http://www.ferrotec.com/usa/domain_detection.htm; and    http://www.rare-earth-magnets.com/detail.aspx?ID=6.
When a ferrofluid surrounded by a gaseous environment is placed in a container and its temperature is its boiling temperature, the liquid portion thereof evaporates. If this process takes place in a situation where the gas is flowing, then the magnetic particles are swept along into the gas stream. Hereinafter, by ‘ferrogas’ is meant hereinafter a mixture of two gases, one being the vapors of the ferrofluid and the other being the carrier gas (e.g., air or CO2), which carries the magnetic particles. By ‘carrier gas’ is meant herein the gaseous atmosphere initially surrounding the ferrofluid.
By ‘ferromixture’ is meant hereafter a combination of ferrofluid and ferrogas. Depending on the location of the magnetic particles in the converter, they may be suspended in a ferrofluid, ferrogas or ferromixture.
It is an object of the invention to provide an apparatus which utilizes the magnetic characteristics of ferrofluid to produce electric energy.
It is another object of the invention to provide an apparatus for converting thermal energy into electricity with a higher efficiency then the conversion efficiency in conventional technologies.
Other objects and advantages of the invention will become apparent as the description proceeds